In the debate about how to meet the world’s increasing energy needs while warding off environmental catastrophe, coal is the elephant in the room. However many windfarms, biomass plants, nuclear power stations and other non-CO2-emitting sources of electricity are built, coal will continue to be the main source of the world’s power generation for many years to come. This is because of the immense quantities of coal reserves remaining to be exploited—mostly in China, the US and India—and because coal-fired power is cheaper than the alternatives. Clean-coal technology offers a means to minimise harmful emissions from this dirtiest member of the fossil fuel family, but it is expensive and as yet untested in large-scale commercial application.

Public concerns about CO2 emissions in the West, allied to increasingly tough regulations, have prompted power developers in to consider serious investments in clean coal, despite the apparent cost disadvantages. The credentials for such projects make impressive reading, but what will it take to turn them into a global industry standard? And is acknowledging coal’s continued supremacy in the world’s energy mix, in effect, a recognition of failure for the effort to chart a greener future?

Bucks for your megawatt
Coal-fired plants currently account for about 40% of the world’s electricity production. World power demand is likely to double over the next 25 years, according to the International Energy Agency (which would still leave 1.5bn people without electricity). Much of the new capacity will come from combined cycle gas turbines, which are the cheapest plants to build, at about US$600 per kw, half the cost of a typical coal steam plant and a quarter of the cost of a nuclear power station. However, gas prices have risen in tandem with the oil price, and gas-based power plants are relatively expensive to run, with costs of between 5 and 7 US cents per kwh, compared with 4 to 6 cents for coal, depending on the region of the world.

The classic clean-coal power station is reckoned to be only slightly more expensive to build than a coal steam plant, and is cheaper to run that its gas turbine equivalent. The integrated gasification combined cycle (IGCC) model entails the conversion of coal into synthetic gas, which can generate electricity in the same way as the purest forms of natural gas. When this is combined with techniques to capture the CO2 emitted, for example through pumping it into depleted oil or gas reservoirs, the process has the potential to produce virtually carbon-free electricity.

One such project has been proposed by Centrica—the owner of British Gas—on Teesside, a heavy industrial area in northeast England. The company claims that for each 1,000 kwh of power produced the plant would emit 0.15 tonnes of carbon, compared with 0.9 tonnes from a traditional coal-fired power plant and 0.45 tonnes from a gas turbine plant. The project is one of three major IGCC schemes planned in the UK alone. E.ON and RWE, two German-owned utilities, have proposed to build similar plants in Lincolnshire and in Tilbury, in the Thames estuary, respectively. RWE is also aiming to set a new benchmark for carbon capture with a clean-coal project in Germany, which would store the CO2 onshore, rather than beneath the sea.

The interest of major power utilities such as these in investing in major clean-coal projects offers the prospect of the costs of IGCC plants being reduced through economies of scale and by market-driven technological innovation. The IEA reckons that over the next 25 years 144,000 mw of IGCC capacity, representing about 200 large power stations, will be commissioned, half of them in the US. That would only account for a fraction of the new coal-fuelled capacity coming on stream worldwide. However, if industry and governments could come up with a financial model tilting the balance in favour of IGCC, there just might be a case for making coal the clean energy source of choice for the future.